Multi-year remote-sensing measurements of gasoline light-duty vehicle emissions on a freeway ramp

On-road optical remote-sensing measurements of gasoline light-duty vehicle (LDV) emissions - CO, HC, NO - were conducted on a freeway ramp in Gothenburg, Sweden, in 1991, 1995 and 1998. Based on almost 30,000 emission measurements, the results show that both catalyst cars and non-catalyst cars emissions deteriorate over time, but also that the emission performance of new TWC-cars has improved significantly in recent years. Furthermore, it was found that fleet age rather than model year determines the rate of emission deterioration for TWC-cars for both CO and NO. The study demonstrates that remote sensing may constitute a powerful tool to evaluate real-world LDV emissions; however, daily held calibration procedures need to be developed in order to assure that the evolution in fleet average emissions can be accurately measured. (C) 2000 Elsevier Science Ltd. All rights reserved.